The invention relates to a computer-controlled, modular microscopy system that produces a magnified video image of a specimen of interest. All microscope components are contained within a sealed enclosure, with the positions of all moving parts of the microscope being controlled from a computer. The invention also relates to an optical system for use with a video camera, where the optical system magnifies an image to be recorded by the camera.
Microscopes are conventionally-used optical instruments in a variety of fields where workers need clear images of structures too small to be seen by the naked eye. For example, medical professionals, biologists, and cytologists conventionally use microscopes to observe cell cultures or uni- or multicellular organisms, while electronics specialists conventionally use microscopes to study silicon wafers.
State-of-the-art microscopes consist of several assemblies that are attached to provide a functioning system. The major assemblies are the stand, a stage adapted to hold a sample, a lens turret having one or more objective lenses, an observation tube having one or two ocular lenses, and a means of illuminating a sample. The objective lens magnifies an image of the sample; the magnified image is then directed into the observation tube. The foundation for a conventional microscopy system is the stand, which typically accounts for about 25% of the system price. The stand provides a stationary platform to hold the imaging and illumination optics. The stage is typically attached to the stand using a rack-and-pinion structure. This allows the stage to travel vertically toward the objective lens, or away from the objective lens, so as to focus the sample image seen through the observation tube.
The stage and observation tube may be arranged in either of two ways. In an upright microscope, the stage is positioned beneath the observation tube, with the objective lens being directed toward the sample. In an inverted microscope, the stage is positioned above the observation tube, with the objective lens being directed toward the sample. Whether the microscope is upright or inverted, the sample may be illuminated by transmitted light or by incident. In a transmitted light illumination system, a beam of light bearing an image of the sample is produced by shining a beam of light through the sample. In an incident light system, a beam of light bearing an image of the sample is produced by reflecting a beam of light off of the sample.
In addition to the above-described components, accessory assemblies such as still or video cameras, filters, or polarizers may be added to the microscope. Cameras are particularly useful accessories, as they allow a researcher to record an image for later study. However, most microscopes are designed to permit viewing of an image by the human eye, forcing the researcher to set up a special apparatus to support the camera above the ocular lens, and then carefully focus the image onto the imaging plane of the camera.
It is also known to control the distance between the microscope stage and the objective lens by computer, so as to provide automatic focus. For example, if the computer determines that the distance between the microscope stage and the objective lens is incorrect for the objective lens, the computer can send a signal to a motor, which moves the stage toward or away from the objective lens. If the microscope has a rotary revolver having a plurality of objective lenses, a revolver position-detecting device may determine which lens is in the optical path. If a lens having the wrong magnification is in the optical path, a signal is sent from the computer to a motor, which rotates the revolver until the correct lens is in the optical path.
People that use optical microscopes have long been asking microscope designers to make microscopes more suitable for human use. The typical microscopist sits hunched over on a laboratory stool, peering downward through the ocular lens of his microscope, in a position guaranteed to cause severe back pain, neck pain, and/or eye strain. In fact, K. S. Lee and L. A. Humphreys, at the 29th Annual Meeting of the Proceedings of the Human Factors Society, reported that 84% of microscopists had job-related musculoskeletal pain. This forces many or most microscopists to leave the profession in considerably under ten years. In many cases, back or neck surgery is necessary to relieve job-related pain sufficiently to allow the microscopist to lead a normal life.
It has been suggested that this sorry statistic could be greatly reduced by using microscopes that display images on computer monitors. Additionally, conventional bench microscopes are designed so that handicapped people or people confined to wheelchairs have trouble reaching the eyepiece, making it difficult for them to pursue careers in microscopy. It is necessary to develop microscopes that can readily be used by the disabled. Microscopes that display images on computer monitors can be used in this way.
It is a first object of this invention to prepare a microscopy system having a video camera as an integral component, where the camera provides a detailed video image of a sample. The image of the sample is focused directly onto the imaging plane of the video camera. This makes the laborious steps of mounting a camera above an ocular lens and readjusting the focus of the microscope image onto the imaging plane unnecessary.
It is a second object of this invention to prepare microscopy systems that can be used without causing job-related musculoskeletal pain.
It is a third object of this invention to prepare microscopy systems that can be easily used by handicapped and/or injured microscopists.
It is a fourth object of this invention to provide a microscope, which can be used, for polarized light microscopy through the simple insertion of a polarizing filter into the microscopes illumination system, without requiring the use of an expensive, high-precision rotating stage.
The second and third objects are achieved by providing microscopes where magnified images are viewed on a video screen and where the positions of all moving parts (the stage, the objective lens, etc.) are remotely controlled from a computer.
This invention provides an improved computer-controlled video microscopy system. The key component of this system is an improved objective lens turret, comprising a cylindrical drum having a tubular sidewall, an open end, a dosed end, and an axis of rotation. A plurality of objective lenses, typically from three to twenty objective lenses, are evenly spaced about the tubular side wall of the cylindrical drum. All of the objective lenses are directed perpendicularly to the drum""s axis of rotation. A light beam carrying an image of a sample to be observed enters the cylindrical drum perpendicularly to the axis of rotation of the drum through one of the objective lenses. A right angle prism, mirror, or other optical element then directs the light beam out of the cylindrical drum through the drum""s open end. Typically, the light beam exits the cylindrical drum parallel to the drum""s axis of rotation. Finally, the objective lens turret comprises a computer-controlled means of selecting one of the objective lenses and rotating the cylindrical drum about its axis of rotation until the selected objective lens enters the path of the light beam.
The microscopy system is also distinguished in that the eyepiece has been done away with and been replaced with a video camera. A lens system focuses the image carried by the light beam exiting the cylindrical drum onto the imaging plane of the video camera, which may be used to transmit the image to a video monitor. This video image can be closely observed for extended periods without causing eyestrain or back pain. Handicapped workers can also view the video image without difficulty.
Other key components of the system include a stage, preferably a motorized stage that can automatically position a sample in the microscope""s field-of-view. The system also includes illumination optics for producing the beam of light carrying the sample image. The individual components of the illumination optics can easily be removed and replaced with other components, including lenses, polarizers, and/or filters. This allows a great deal of flexibility in using the microscope.
The objective lens turret and the video camera are attached to a vertical plate via linear bearings or a rack-and-pinion system and move vertically under computer control to provide image focus.